Bug Out: Winter tips to reduce garden insects & disease

Close up of a weevil on a green leaf.

Taking the time to properly prepare your garden for winter has a long list of benefits. One of the biggies is that you can protect your garden from many destructive insects and diseases. Standard pre-winter gardening tasks serve multiple purposes—including deterring pests and disease simply by disturbing their winter habitat. By adding a step or two to your usual routine, you may find yourself significantly less pestered in the garden next year.

 1. Remove dead and diseased plant material

Diseases such as late blight can successfully overwinter on plant material that is left in your garden. Weeds and other debris serve as perfect breeding places for many of our insect foes. Be sure to remove all weeds, dead foliage, and fruit before the snow flies. Dispose of diseased material by bringing it to a commercial compost facility. You can also bury the material deeply, or if there is no other option, put it in sealed containers for disposal with household trash.

2. Bring out the grubs!

Some of the coldest weeks in winter present a prime opportunity for gardeners. Many insects, including beetles, spend the winter in a semi-dormant larval or “grub” state. Grubs dig themselves down into soil and situate themselves below the frost line, where conditions are cozy enough for survival.

As winter weather sets in—but before the ground freezes—gently turn up the first few inches of your soil, in beds and around fruit trees, with a border fork to bring grubs toward the surface. (This is a great opportunity to work some compost into the soil!) Now exposed, they will meet their demise via the grip of frost or the beaks of hungry birds.

How deeply you till depends on your personal preferences, but keep in mind that most grubs are situated 2”-8” inches below the surface. If your soil is covered by mulch, simply peel back the mulch before turning the soil. Leave the soil of mulched areas exposed for 3 or 4 of the coldest weeks of winter to “clean” the soil before replacing the mulch.

3. Build your soil 

Top-dressing your soil with compost is a great way to develop strong, vigorous plants that are less susceptible to damage from disease and insects. After your fall clean-up, add 2”-6” of compost. Check out our Compost Coverage Calculator to figure out how much compost you need based on the size of your garden.

4. Winter Wash

One more handy weapon in our fight against garden pests is the winter wash. After the leaves have fallen, generously spray the branches of shrubs and fruit trees with a plant oil- or fish oil-based solution to smother residing bugs, including aphids and mites. By controlling these insects, you are simultaneously reducing the emergence of viruses—a double whammy!

All living things need a functioning habitat to survive. Removing key habitat components of pests that overwinter in your garden is an easy, safe, and inexpensive way to de-bug the system for a healthier and more productive garden next spring.

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